Is it normal that new field, Field Data options are Virtual; prevent Entry and Summarize is selected?

Getting this weird behaviour when adding any field and Summarize has to be unselected to prevent the 'Missing operator' error

No.

We have never seen this before.

A new field should normally not have Sumarize selected.

Is this a field in a form that does not define table or in a report etc.

See now what caused it although reason is not clear.

Form was created from Save As of 'Template - Toolbar Grey'

'Define New Table' was selected and it is a table owning form.

New forms created with new fields are ok.